1. OBJECT 4 ATMOSPHERE ESSENTIAL QUESTIONS
How can atmospheric pollution be
controlled?
What are the problems involved with
the local and global management of
atmospheric Pollution?

3. Central Case Study: Rising Seas May Flood the Maldives
Tourists think the Maldives Islands are a paradise
Rising seas due to global climate change could submerge them
Flood areas, erode beaches
Damage coral reefs
Residents have evacuated the lowest-lying islands
Small nations do not cause of climate change
Yet they suffer

4. Three factors influence Earth’s climate
The sun: without it, Earth would be dark and frozen
It supplies most of Earth’s energy
The atmosphere: without it, Earth’s temperature would be much colder
Clouds, land, ice, and water absorb 70% of incoming solar radiation
The remaining 30% is reflected back into space
The oceans: shape climate by storing and transporting heat and moisture

5. The fate of solar radiation

6. Greenhouse gases warm the lower atmosphere
As Earth’s surface absorbs solar radiation, the surface temperature increases and emits infrared radiation
Greenhouse gases: atmospheric gases that absorb infrared radiation
Water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons (chlorofluorocarbons [CFCs])
Greenhouse gases re-emit infrared energy
Some energy is lost to space
Greenhouse effect: the energy that travels downward warms the atmosphere and the planet’s surface

7. Greenhouse gases are not all equal
Greenhouse gases differ in their ability to warm the trophosphere and surface
Global warming potential: the relative ability of one molecule of a greenhouse gas to contribute to warming
Expressed in relation to carbon dioxide (potential = 1)
Nitrous oxide is 298 times as potent as carbon dioxide
Carbon dioxide contributes most to the greenhouse effect
It is less potent, but far more abundant, than other gases
The major type of human-caused emissions

8. Greenhouse gas concentrations are rising
The greenhouse effect is natural
Greenhouse gases have always been in the atmosphere
We are concerned with the anthropogenic (human-caused) intensification of the greenhouse effect
We have increased the concentration of these gases beyond what we have ever experienced
CO2 has increased from 280 ppm (1700s) to 389 ppm
The highest in 800,000 (possibly 20 million) years

9. U.S. emissions of major greenhouse gases

10. Why have CO2 levels risen so rapidly?
Burning fossil fuels transfers CO2 from underground deposits into the atmosphere
The main reason CO2 levels have increased
Deforestation contributes to rising atmospheric CO2
Plants store carbon in their tissues
Less CO2 is absorbed from the atmosphere

11. Other greenhouse gases are increasing
Methane: fossil fuels, livestock, landfills, crops (rice)
Levels have increased 2.5 times since 1750
Nitrous oxide: feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers
Risen 18% since 1750
Ozone levels have risen 36% due to photochemical smog
The Montreal Protocol has reduced halocarbons (CFCs)
Water vapor: the most abundant greenhouse gas
Contributes most to the natural greenhouse effect
But concentrations have not changed

12. Most aerosols exert a cooling effect
Aerosols: microscopic droplets and particles
They have either a warming or a cooling effect
Soot (black carbon aerosols) causes warming by absorbing solar energy
But most tropospheric aerosols cool the atmosphere by reflecting the sun’s rays
Sulfate aerosols from fossil fuel combustion may slow global warming, at least in the short term
Volcanic eruptions reduce sunlight reaching Earth’s surface and cool the Earth
Cooling can mask real results

13. Milankovitch cycles also influence climate
Milankovitch cycles: periodic changes in Earth’s rotation and orbit around the sun
Alter the way solar radiation is distributed over Earth
These cycles modify patterns of atmospheric heating
Triggering climate variation
Glaciation: cold temperatures and ice sheets

14. Solar output and oceans influence climate
Solar output: the sun varies in the radiation it emits
Variation in solar energy (e.g., solar flares) has not been great enough to change Earth’s temperature
Radiative forcing is 0.12 watts/m2 —less than any human causes
Ocean absorption: oceans hold 50 times more carbon than the atmosphere
Slows global warming but does not prevent it
As oceans warm, they absorb less CO2, accelerating warming

15. Proxy indicators tell us about the past
Proxy indicators: indirect evidence that serve as substitutes for direct measurements of past climate
Ice caps, ice sheets, and glaciers hold clues to Earth’s climate history
Trapped bubbles in ice cores provide a timescale of:
Atmospheric composition, greenhouse gas concentrations, temperature, snowfall, solar activity
Frequency of fires and volcanic eruptions
Other indicators include pollen preserved in sediment, tree rings, pack-rat middens, coral reefs

16. 800,000 years of history in an ice core
Concentrations of gas are correlated with temperature
Trapped bubbles contain samples of ancient air

17. Direct measurements tell us about the present
We document daily fluctuations in weather
Temperature, rainfall, wind speed, air pressure
Measuring ocean and atmospheric chemistry began in 1958
Hourly air samples from Mauna Loa Observatory in Hawaii show that…
Atmospheric CO2 concentrations have increased from 315 ppm to 389 ppm since 1958

18. Models help us predict the future
Climate models: combine data from atmospheric and ocean circulation and interactions
To simulate climate processes
If a model accurately reconstructs current climate
It may accurately predict future climate
Modeling is hard because climate and feedback loops are so complex

19. Current and future trends and impacts
Evidence that climate has changed is everywhere
Fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc.
We cannot blame any single weather event on climate change
But extreme weather is part of a pattern backed by an immense volume of scientific data
The Intergovernmental Panel on Climate Change (IPCC) was established in 1988
Composed of hundreds of international scientists and government representatives

20. The IPCC’s Fourth Assessment Report (2007)
The IPCC report summarized thousands of studies
It documented observed trends in:
Surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, etc.
It predicted future changes on wildlife, ecosystems, and human societies
It discussed strategies to pursue in response to climate change
The authors assigned statistical probabilities to its conclusions and released conservative estimates

21. The IPCC’s Fourth Assessment Report (2007)

22. Temperatures continue to increase
Average surface temperatures increased 0.74 °C since 1906
Most of the increase occurred in the last few decades
The 17 warmest years on record have been since 1990
Since the 1960s, each decade has been warmer than the last

23. The future will be even hotter
In the next 20 years, temperatures will rise 0.4C
At the end of the 21st century, temperatures will be 1.8 to 4.0C higher than today’s
We will have unusually hot days and heat waves
Polar areas will have the most intense warming
Sea surface temperatures will rise
Hurricanes and tropical storms will increase in power and duration

24. Temperatures will rise globally
Projected increases in surface temperature for 2090–2099 relative to 1980–1999

25. Precipitation is changing, too
Some regions are receiving more rain and snow
Other areas are receiving less
In the U.S. Southwest, droughts have become more frequent and severe
Harm agriculture, promote soil erosion, reduce water supplies, and trigger fires
In dry, humid regions, heavy rains cause flooding
Kill people, destroy homes, and inflict billions of dollars in damage
Example: 2008 floods in Iowa and the Midwest

26. Projected changes in precipitation
Precipitation will increase at high latitudes and decrease at low and middle latitudes – worsening water shortages in poor nations

27. Melting of snow and ice has severe effects
Mountaintop glaciers are disappearing
Glaciers on tropical mountaintops have disappeared
The remaining 26 of 150 glaciers in Glacier National Park will be gone by 2030
Reducing summertime water supplies to millions
Melting of Greenland’s Arctic ice sheet is accelerating
Warmer water is melting Antarctica’s coastal ice shelves
Interior snow is increasing due to more precipitation
Melting ice exposes darker, less-reflective (lower albedo) surfaces, which causes even more melting

28. Worldwide, glaciers are melting rapidly
Nations are rushing to exploit underwater oil and mineral resources made available by newly opened shipping lanes
Permafrost (permanently frozen ground) is thawing
Destabilizing soil, buildings, etc., and releasing methane
Montana’s Grinnell Glacier has retreated substantially since 1938

29. Rising sea levels will affect millions
Runoff from melting glaciers and ice cause sea levels to rise
As oceans warm, they expand
Leading to beach erosion, coastal floods, intrusion of salt water into aquifers, and storm surges

30. Coastal areas will flood
Storm surge: temporary, localized rise in sea level
Caused by the high tides and winds of storms
A 2004 earthquake caused a tsunami (tidal wave) that killed 100 Maldives residents
Caused $470 million in damages
Cities will be flooded
53% of people in the U.S. live in coastal areas
Vulnerability to storm surges will increase
Rising seas eliminate marsh grasses; dams stop sediment from replenishing deltas

31. Rising sea levels will devastate coasts
Rising seas will displace millions of people from coastal areas
Many will have to invest in costly efforts to protect against high tides and storm surges
Areas that will be most affected include:
Densely populated, poor regions (e.g., Bangladesh)
Storm-prone regions (e.g., Florida)
Coastal cities (e.g., Houston)
Areas with land subsidence (e.g., U.S. Gulf Coast)
Pacific Islands will have to be evacuated

32. Coral reefs are threatened
Coral reefs are habitat for marine species, tourism destinations, and protect coastlines
Warmer waters contribute to coral bleaching
Which kills corals
Ocean acidification: caused by increased CO2
Organisms can’t build their exoskeletons
Oceans have already decreased by 0.1 pH unit
They will decrease 0.15 to 0.35 more units—enough to kill most coral reefs, which will be catastrophic

33. Endangered Natural Capital: Biodiversity Hotspots in the U.S.33

34. Organisms and ecosystems are affected
Organisms are adapted to their environments
They are affected when those environments change
Global warming modifies temperature-dependent phenomena (e.g., timing of migration, breeding)
Species will move toward the poles or up in elevation
20–30% of species will be threatened with extinction
Rare species will be pushed out of preserves
More CO2 may increase plant growth, but…
Droughts, fire, and disease will decrease plant growth
Fewer plants means more CO2 in the atmosphere

35. Animals and plants have nowhere to go
Animals and plants adapted to montane environments will be forced uphill until there is no place to go
Many bird species have shifted their ranges northward in the past 40 years

36. Climate change affects society
Societies are already feeling impacts of climate change
Agriculture: shortened growing seasons, decreased production, crops more susceptible to droughts
Increasing hunger in many developing nations
Forestry: increased fires, invasive species
Insect and disease outbreaks
Health: heat waves and stress can cause death
Respiratory ailments, expansion of tropical diseases
Disease and sanitation problems from flooding
Drowning from storms

37. Climate change affects economics
Costs will outweigh benefits of climate change
It will widen the gap between rich and poor
Those with less wealth and technology will suffer most
It will cost 1–5% GDP on average globally
Poor nations will lose more than rich ones
The Stern Review on the Economics of Climate Change predicts it will cost 5–20% of GDP by 2200
Investing 1% of GDP now could avoid these costs

38. Global Warming and Climate Change

39. Impacts will vary regionally
Where we live will determine how we experience the impacts of climate change
Temperature changes have been greatest in the Arctic
Melting ice sheets, thinning ice, increasing storms, etc.
Harder for people and polar bears to hunt

40. The U.S. Global Change Research Program
In their 2009 report, scientists reported and predicted:
Temperature increases (2.2 – 6.1C higher)
Worse droughts and flooding
Decreased crop yields
Water shortages
Health problems and diseases
Higher sea levels, beach erosion, destroyed wetlands
Drought, fire, and pests will change forests
More grasslands and deserts, fewer forests
Undermined Alaskan buildings and roads

41. Predictions from two climate models
Temperature increases will be much smaller if emissions are lowered

42. Causes and consequences of climate change